docs: def to_camel_case(underscore_case, mixed=False):
      r"""
      Args:
          underscore_case (?):
  
      Returns:
          str: camel_case_str
  
      CommandLine:
          python -m utool.util_str --exec-to_camel_case
  
      References:
          https://en.wikipedia.org/wiki/CamelCase
  
      Example:
          >>> # ENABLE_DOCTEST
          >>> from utool.util_str import *  # NOQA
          >>> underscore_case = 'underscore_funcname'
          >>> camel_case_str = to_camel_case(underscore_case)
          >>> result = ('camel_case_str = %s' % (str(camel_case_str),))
          >>> print(result)
          camel_case_str = UnderscoreFuncname
      """
      thresh = 0 if mixed else -1
      words = underscore_case.split('_')
      words2 = [
          word[0].upper() + word[1:]
          if count > thresh else
          word
          for count, word in enumerate(words)
      ]
      camel_case_str = ''.join(words2)
      return camel_case_str