code: def remove_leading(needle, haystack):
      
      if haystack[:len(needle)] == needle:
          return haystack[len(needle):]
      return haystack
docs: Remove leading needle string (if exists).
  
      >>> remove_leading('Test', 'TestThisAndThat')
      'ThisAndThat'
      >>> remove_leading('Test', 'ArbitraryName')
      'ArbitraryName'