code: def prefixedDec(nstr, schema):
      
      if not nstr.startswith(schema):
          return False
      postfix = nstr[len(schema):]
      try:
          int(postfix)
      except ValueError:
          return False
      return True
docs: !~~prefixedDec
          corresponding strings in documents must begin with the
          associated string in the schema, and the right part of strings
          in documents must be decimal.