code: def public_pair_to_sec(public_pair, compressed=True):
      
      x_str = to_bytes_32(public_pair[0])
      if compressed:
          return int2byte((2 + (public_pair[1] & 1))) + x_str
      y_str = to_bytes_32(public_pair[1])
      return b'\4' + x_str + y_str
docs: Convert a public pair (a pair of bignums corresponding to a public key) to the
      gross internal sec binary format used by OpenSSL.