remove problematic regex check

Author: daniel-sanche

google/cloud/firestore_v1/field_path.py

@@ -31,7 +31,6 @@
 _ESCAPED_BACKTICK = _BACKSLASH + _BACKTICK
 
 _SIMPLE_FIELD_NAME = re.compile("^[_a-zA-Z][_a-zA-Z0-9]*$")
-_LEADING_ALPHA_INVALID = re.compile("^[_a-zA-Z][_a-zA-Z0-9]*[^_a-zA-Z0-9]")
 PATH_ELEMENT_TOKENS = [
     ("SIMPLE", r"[_a-zA-Z][_a-zA-Z0-9]*"),  # unquoted elements
     ("QUOTED", r"`(?:\\`|[^`])*?`"),  # quoted elements, unquoted
@@ -309,12 +308,6 @@ def from_string(cls, path_string: str):
             for element in elements:
                 if not element:
                     raise ValueError("Empty element")
-                if _LEADING_ALPHA_INVALID.match(element):
-                    raise ValueError(
-                        "Non-alphanum char in element with leading alpha: {}".format(
-                            element
-                        )
-                    )
             return FieldPath(*elements)
 
     def __repr__(self):