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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 encode_function_call(self, function_name, args):
 """ Return the encoded function call. Args: function_name (str):
 One of the existing functions described in the contract interface. args (List[object]):
 The function arguments that wll be encoded and used in the contract execution in the vm. Return: bin: The encoded function name and arguments so that it can be used with the evm to execute a funcion call, the binary string follows the Ethereum Contract ABI. """

        if function_name not in self.function_data:
            raise ValueError('Unkown function {}'.format(function_name))

        description = self.function_data[function_name]

        function_selector = zpad(encode_int(description['prefix']), 4)
        arguments = encode_abi(description['encode_types'], args)

        return function_selector + arguments