code: def to_python(self, value):
          
          res = super(VaryingTypeCharField, self).to_python(value)
          split_res = res.split(self._default_separator)
          if not res or len(split_res) < 2:
              return res.strip()
  
          # create a regex string out of the list of choices passed, i.e: (a|b)
          res = r"({pattern})".format(pattern="|".join(
              map(lambda x: x.strip(), split_res)))
          return res
docs: Split a string value by separator (default to ",") into a
          list; then, returns a regex pattern string that ORs the values
          in the resulting list.
  
          >>> field = VaryingTypeCharField()
          >>> assert field.to_python('') == ''
          >>> assert field.to_python('test') == 'test'
          >>> assert field.to_python('and,me') == '(and|me)'
          >>> assert field.to_python('and,me;too') == '(and|me;too)'