diff --git a/mathics/core/definitions.py b/mathics/core/definitions.py
index 8213879e6..bd2d8d3bf 100644
--- a/mathics/core/definitions.py
+++ b/mathics/core/definitions.py
@@ -15,7 +15,7 @@
 from mathics.core.convert.expression import to_mathics_list
 from mathics.core.element import fully_qualified_symbol_name
 from mathics.core.expression import Expression
-from mathics.core.load_builtin import definition_contribute, modules
+from mathics.core.load_builtin import definition_contribute, mathics3_builtins_modules
 from mathics.core.symbols import Atom, Symbol, strip_context
 from mathics.core.systemsymbols import SymbolGet
 from mathics.settings import ROOT_DIR
@@ -139,10 +139,12 @@ def __init__(
         self.timing_trace_evaluation = False
 
         if add_builtin:
-
             loaded = False
             if builtin_filename is not None:
-                builtin_dates = [get_file_time(module.__file__) for module in modules]
+                builtin_dates = [
+                    get_file_time(module.__file__)
+                    for module in mathics3_builtins_modules
+                ]
                 builtin_time = max(builtin_dates)
                 if get_file_time(builtin_filename) > builtin_time:
                     builtin_file = open(builtin_filename, "rb")
@@ -769,7 +771,6 @@ def __init__(
         builtin=None,
         is_numeric=False,
     ) -> None:
-
         super(Definition, self).__init__()
         self.name = name
 
diff --git a/mathics/core/load_builtin.py b/mathics/core/load_builtin.py
index a40399b84..a2a3453e2 100755
--- a/mathics/core/load_builtin.py
+++ b/mathics/core/load_builtin.py
@@ -12,6 +12,7 @@
 import os.path as osp
 import pkgutil
 from glob import glob
+from types import ModuleType
 from typing import List, Optional
 
 from mathics.core.pattern import pattern_objects
@@ -19,14 +20,17 @@
 from mathics.eval.makeboxes import builtins_precedence
 from mathics.settings import ENABLE_FILES_MODULE
 
-# List of Mathics3 Builtin modules.
-# This is initialized via below import_builtins modules
-modules = []
+# List of Python modules contain Mathics3 Builtins.
+# This list used outside to gather documentation,
+# and test module consistency. It is
+# is initialized via below import_builtins modules
+mathics3_builtins_modules: List[ModuleType] = []
 
 _builtins = {}
 builtins_by_module = {}
 display_operators_set = set()
 
+
 # The fact that are importing inside here, suggests add_builtins
 # should get moved elsewhere.
 def add_builtins(new_builtins):
@@ -56,7 +60,7 @@ def add_builtins(new_builtins):
     _builtins.update(dict(new_builtins))
 
 
-def add_builtins_from_builtin_modules(modules):
+def add_builtins_from_builtin_modules(modules: List[ModuleType]):
     # This can be put at the top after mathics.builtin.__init__
     # cleanup is done.
     from mathics.builtin.base import Builtin
@@ -129,7 +133,7 @@ def import_and_load_builtins():
     )
     exclude_files = {"codetables", "base"}
     module_names = get_module_names(builtin_path, exclude_files)
-    import_builtins(module_names, modules)
+    import_builtins(module_names, mathics3_builtins_modules)
 
     # Get import modules in subdirectories of this directory of Python
     # modules that contain Mathics3 Builtin class definitions.
@@ -140,16 +144,20 @@ def import_and_load_builtins():
     disable_file_module_names = set() if ENABLE_FILES_MODULE else {"files_io"}
 
     subdirectories = next(os.walk(builtin_path))[1]
-    import_builtin_subdirectories(subdirectories, disable_file_module_names, modules)
+    import_builtin_subdirectories(
+        subdirectories, disable_file_module_names, mathics3_builtins_modules
+    )
 
-    add_builtins_from_builtin_modules(modules)
+    add_builtins_from_builtin_modules(mathics3_builtins_modules)
     initialize_display_operators_set()
 
 
 # TODO: When we drop Python 3.7,
 # module_names can be a List[Literal]
 def import_builtins(
-    module_names: List[str], modules: list, submodule_name: Optional[str] = None
+    module_names: List[str],
+    modules: List[ModuleType],
+    submodule_name: Optional[str] = None,
 ):
     """
     Imports the list of Mathics3 Built-in modules so that inside
@@ -210,7 +218,7 @@ def initialize_display_operators_set():
                 display_operators_set.add(operator)
 
 
-def name_is_builtin_symbol(module, name: str) -> Optional[type]:
+def name_is_builtin_symbol(module: ModuleType, name: str) -> Optional[type]:
     """
     Checks if ``name`` should be added to definitions, and return
     its associated Builtin class.
diff --git a/mathics/doc/common_doc.py b/mathics/doc/common_doc.py
index a5e4e59a5..617c43e27 100644
--- a/mathics/doc/common_doc.py
+++ b/mathics/doc/common_doc.py
@@ -36,7 +36,7 @@
 from mathics.core.evaluation import Message, Print
 from mathics.core.load_builtin import (
     builtins_by_module as global_builtins_by_module,
-    modules as mathics3_builtin_modules,
+    mathics3_builtins_modules,
 )
 from mathics.core.util import IS_PYPY
 from mathics.doc.utils import slugify
@@ -114,7 +114,8 @@
 SUBSECTION_RE = re.compile('(?s)<subsection title="(.*?)">')
 
 TESTCASE_RE = re.compile(
-    r"""(?mx)^  # re.MULTILINE (multi-line match) and re.VERBOSE (readable regular expressions
+    r"""(?mx)^  # re.MULTILINE (multi-line match)
+                # and re.VERBOSE (readable regular expressions
         ((?:.|\n)*?)
         ^\s+([>#SX])>[ ](.*)  # test-code indicator
         ((?:\n\s*(?:[:|=.][ ]|\.).*)*)  # test-code results"""
@@ -125,12 +126,6 @@
 test_result_map = {}
 
 
-def _replace_all(text, pairs):
-    for i, j in pairs:
-        text = text.replace(i, j)
-    return text
-
-
 def get_module_doc(module: ModuleType) -> tuple:
     doc = module.__doc__
     if doc is not None:
@@ -638,7 +633,7 @@ def gather_doctest_data(self):
         for title, modules, builtins_by_module, start in [
             (
                 "Reference of Built-in Symbols",
-                mathics3_builtin_modules,
+                mathics3_builtins_modules,
                 global_builtins_by_module,
                 True,
             )
diff --git a/mathics/doc/latex_doc.py b/mathics/doc/latex_doc.py
index d17f6f7cc..8dc6a53e0 100644
--- a/mathics/doc/latex_doc.py
+++ b/mathics/doc/latex_doc.py
@@ -35,7 +35,6 @@
     DocText,
     Documentation,
     XMLDoc,
-    _replace_all,
     gather_tests,
     get_results_by_test,
     post_sub,
@@ -104,7 +103,7 @@ def repl_python(match):
 
     text, post_substitutions = pre_sub(PYTHON_RE, text, repl_python)
 
-    text = _replace_all(
+    text = replace_all(
         text,
         [
             ("\\", "\\\\"),
@@ -120,7 +119,7 @@ def repl_python(match):
     def repl(match):
         text = match.group(1)
         if text:
-            text = _replace_all(text, [("\\'", "'"), ("^", "\\^")])
+            text = replace_all(text, [("\\'", "'"), ("^", "\\^")])
             escape_char = get_latex_escape_char(text)
             text = LATEX_RE.sub(
                 lambda m: "%s%s\\codevar{\\textit{%s}}%s\\lstinline%s"
@@ -163,7 +162,7 @@ def repl_list(match):
     text = LIST_RE.sub(repl_list, text)
 
     # FIXME: get this from MathicsScanner
-    text = _replace_all(
+    text = replace_all(
         text,
         [
             ("$", r"\$"),
@@ -313,7 +312,7 @@ def repl_subsection(match):
 def escape_latex_output(text) -> str:
     """Escape Mathics output"""
 
-    text = _replace_all(
+    text = replace_all(
         text,
         [
             ("\\", "\\\\"),
@@ -448,6 +447,12 @@ def repl_nonasy(match):
     return OUTSIDE_ASY_RE.sub(repl_nonasy, result)
 
 
+def replace_all(text, pairs):
+    for i, j in pairs:
+        text = text.replace(i, j)
+    return text
+
+
 def strip_system_prefix(name):
     if name.startswith("System`"):
         stripped_name = name[len("System`") :]
diff --git a/mathics/main.py b/mathics/main.py
index 067be1bf4..51eb3efbd 100755
--- a/mathics/main.py
+++ b/mathics/main.py
@@ -32,6 +32,10 @@
 from mathics.core.symbols import SymbolNull, strip_context
 from mathics.timing import show_lru_cache_statistics
 
+# from mathics.timing import TimeitContextManager
+# with TimeitContextManager("import_and_load_builtins()"):
+#     import_and_load_builtins()
+
 import_and_load_builtins()
 
 
diff --git a/mathics/version.py b/mathics/version.py
index c36ca72bb..7b0a25141 100644
--- a/mathics/version.py
+++ b/mathics/version.py
@@ -5,4 +5,4 @@
 # well as importing into Python. That's why there is no
 # space around "=" below.
 # fmt: off
-__version__="6.1.0dev0"  # noqa
+__version__="7.0.0dev0"  # noqa
diff --git a/test/consistency-and-style/test_duplicate_builtins.py b/test/consistency-and-style/test_duplicate_builtins.py
index 688310d4d..5ece63ccb 100644
--- a/test/consistency-and-style/test_duplicate_builtins.py
+++ b/test/consistency-and-style/test_duplicate_builtins.py
@@ -9,7 +9,7 @@
 import pytest
 
 from mathics.builtin.base import Builtin
-from mathics.core.load_builtin import modules, name_is_builtin_symbol
+from mathics.core.load_builtin import mathics3_builtins_modules, name_is_builtin_symbol
 
 
 @pytest.mark.skipif(
@@ -18,7 +18,7 @@
 def test_check_duplicated():
     msg = ""
     builtins_by_name = {}
-    for module in modules:
+    for module in mathics3_builtins_modules:
         vars = dir(module)
         for name in vars:
             var = name_is_builtin_symbol(module, name)