Whether this value (presumably global) is defined in the current
        module.

def is_declaration(self):
        """
        Whether this value (presumably global) is defined in the current
        module.
        """
        if not (self.is_global or self.is_function):
            raise ValueError('expected global or function value, got %s'
                             % (self._kind,))
        return ffi.lib.LLVMPY_IsDeclaration(self)