code: def find_signature(self, signature_id=None, signer_email_address=None):
          ''' Return a signature for the given parameters
  
              Args:
  
                  signature_id (str):             Id of the signature to retrieve.
                  signer_email_address (str):     Email address of the associated signer for the signature to retrieve.
  
              Returns:
                  A Signature object or None
  
          '''
          if self.signatures:
              for signature in self.signatures:
                  if signature.signature_id == signature_id or signature.signer_email_address == signer_email_address: 
                      return signaturf find_signature(self, signature_id=None, signer_email_address=None):
          ''' Return a signature for the given parameters
  
              Args:
  
                  signature_id (str):             Id of the signature to retrieve.
                  signer_email_address (str):     Email address of the associated signer for the signature to retrieve.
  
              Returns:
                  A Signature object or None
  
          '''
          if self.signatures:
              for signature in self.signatures:
                  if signature.signature_id == signature_id or signature.signer_email_address == signer_email_address: 
                      return signature
docs: Return a signature for the given parameters
  
              Args:
  
                  signature_id (str):             Id of the signature to retrieve.
                  signer_email_address (str):     Email address of the associated signer for the signature to retrieve.
  
              Returns:
                  A Signature object or None