docs: def from_seedhex(cls: Type[SigningKeyType], seedhex: str) -> SigningKeyType:
          """
          Return SigningKey instance from Seedhex
  
          :param str seedhex: Hexadecimal seed string
          """
          regex_seedhex = compile("([0-9a-fA-F]{64})")
          match = search(regex_seedhex, seedhex)
          if not match:
              raise Exception('Error: Bad seed hexadecimal format')
          seedhex = match.groups()[0]
          seed = convert_seedhex_to_seed(seedhex)
          return cls(seed)