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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 handle_internal_commands(command):
 """Run repl-internal commands. Repl-internal commands are all commands starting with ":". """

    if command.startswith(":"):
        target = _get_registered_target(command[1:], default=None)
        if target:
            return target()