code: def parse_issuer_cred(issuer_cred):
      
      # get each section of the PEM file
      sections = re.findall(
          "-----BEGIN.*?-----.*?-----END.*?-----", issuer_cred, flags=re.DOTALL
      )
      try:
          issuer_cert = sections[0]
          issuer_private_key = sections[1]
          issuer_chain_certs = sections[2:]
      except IndexError:
          raise ValueError(
              "Unable to parse PEM data in credentials, "
              "make sure the X.509 file is in PEM format and "
              "consists of the issuer cert, issuer private key, "
              "and proxy chain (if any) in that order."
          )
  
      # then validate that each section of data can be decoded as expected
      try:
          loaded_cert = x509.load_pem_x509_certificate(
              six.b(issuer_cert), default_backend()
          )
          loaded_private_key = serialization.load_pem_private_key(
              six.b(issuer_private_key), password=None, backend=default_backend()
          )
          for chain_cert in issuer_chain_certs:
              x509.load_pem_x509_certificate(six.b(chain_cert), default_backend())
          issuer_chain = "".join(issuer_chain_certs)
      except ValueError:
          raise ValueError(
              "Failed to decode PEM data in credentials. Make sure "
              "the X.509 file consists of the issuer cert, "
              "issuer private key, and proxy chain (if any) "
              "in that order."
          )
  
      # return loaded cryptography objects and the issuer chain
      return loaded_cert, loaded_private_key, issuer_chain
docs: Given an X509 PEM file in the form of a string, parses it into sections
      by the PEM delimiters of: -----BEGIN <label>----- and -----END <label>----
      Confirms the sections can be decoded in the proxy credential order of:
      issuer cert, issuer private key, proxy chain of 0 or more certs .
      Returns the issuer cert and private key as loaded cryptography objects
      and the proxy chain as a potentially empty string.