code: def issuer_type(self, issuer_type):
          
          if issuer_type is None:
              raise ValueError("Invalid value for `issuer_type`, must not be `None`")
          allowed_values = ["GLOBAL_SIGN", "CFSSL_AUTH"]
          if issuer_type not in allowed_values:
              raise ValueError(
                  "Invalid value for `issuer_type` ({0}), must be one of {1}"
                  .format(issuer_type, allowed_values)
              )
  
          self._issuer_type = issuer_type
docs: Sets the issuer_type of this CertificateIssuerInfo.
          The type of the certificate issuer. - GLOBAL_SIGN:   Certificates are issued by GlobalSign service. The users must provide their own GlobalSign account credentials. - CFSSL_AUTH:   Certificates are issued by CFSSL authenticated signing service.   The users must provide their own CFSSL host_url and credentials. 
  
          :param issuer_type: The issuer_type of this CertificateIssuerInfo.
          :type: str