def unfix(self, param):
if param == "<STR_LIT>":<EOL><INDENT>self._unfix("<STR_LIT>")<EOL><DEDENT>else:<EOL><INDENT>self._fix[param] = False<EOL><DEDENT>
Enable parameter optimization.

Parameters
----------
param : str
    Possible values are ``"delta"``, ``"beta"``, and ``"scale"``.