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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 get_target_variable(self, targets, variable):
 """Gets the value of `variable` on set on the first target in `targets`. Args: targets (str or list):
 one or more targets to get the variable from. variable (str):
 the name of the variable Returns: the value of `variable` set on `targets` (list) Example: ['Hello World'] Equivalent Jam code: MY-VAR on $(targets) = "Hello World" ; echo [ on $(targets) return $(MY-VAR) ] ; "Hello World" """

        if isinstance(targets, str):
            targets = [targets]
        assert is_iterable(targets)
        assert isinstance(variable, basestring)

        return bjam_interface.call('get-target-variable', targets, variable)