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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def parameter_constructor(cls, loader, node):
 """ Construct variable instance from yaml node """

        value = loader.construct_scalar(node)

        if isinstance(value, str):
            if '=' in value:
                (varname, varvalue) = Parser.parse_equality(value)
                return cls(varname, varvalue)
            else:
                return cls(value)
        else:
            return cls(value)