docs: def unCompressed(self):
          """ Derive uncompressed key """
          public_key = repr(self._pk)
          prefix = public_key[0:2]
          if prefix == "04":
              return public_key
          assert prefix == "02" or prefix == "03"
          x = int(public_key[2:], 16)
          y = self._derive_y_from_x(x, (prefix == "02"))
          key = '04' + '%064x' % x + '%064x' % y
          return key