code: def verify(sigfilename, filefilename=None):
      
  
      if gnupg is None:
          return False
  
      gpg = gnupg.GPG()
  
      with open(sigfilename, "rb") as sigfile:
          verified = gpg.verify_file(sigfile, filefilename)
  
          pyspread_keyid = fingerprint2keyid(config["gpg_key_fingerprint"])
  
          if verified.valid and verified.key_id == pyspread_keyid:
              return True
  
      return False
docs: Verifies a signature, returns True if successful else False.