<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def show_xref(self, c_a):
 """ Display where the method is called or which method is called """

        if c_a:
            ref_kind_map = {0: "Class instanciation", 1: "Class reference"}
            bytecode._PrintSubBanner("XREF From")

            xrefs_from = c_a.get_xref_from()
            for ref_class in xrefs_from:
                if ref_class.get_vm_class().get_name() == self.get_name():
                    continue
                for ref_kind, ref_method, ref_offset in xrefs_from[ref_class]:
                    bytecode._PrintDefault(ref_kind_map[ref_kind])
                    bytecode._PrintDefault(' ')
                    bytecode._PrintDefault(ref_method.get_name())
                    bytecode._PrintDefault(' @ 0x%x' % ref_offset)
                    bytecode._PrintDefault('\n')

            bytecode._PrintDefault('\n')

            bytecode._PrintSubBanner("XREF To")
            xrefs_to = c_a.get_xref_to()
            for ref_class in xrefs_to:
                if ref_class.get_vm_class().get_name() == self.get_name():
                    continue
                bytecode._PrintDefault(ref_class.get_vm_class().get_name())
                bytecode._PrintDefault(' -->\n')
                for ref_kind, ref_method, ref_offset in xrefs_to[ref_class]:
                    bytecode._PrintDefault(ref_kind_map[ref_kind])
                    bytecode._PrintDefault(' ')
                    bytecode._PrintDefault(ref_method.get_name())
                    bytecode._PrintDefault(' @ 0x%x' % ref_offset)
                    bytecode._PrintDefault('\n')