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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 force_rerun(flag, outfile):
 """Check if we should force rerunning of a command if an output file exists. Args: flag (bool):
 Flag to force rerun. outfile (str):
 Path to output file which may already exist. Returns: bool: If we should force rerunning of a command Examples: True True True False """

    # If flag is True, always run
    if flag:
        return True
    # If flag is False but file doesn't exist, also run
    elif not flag and not op.exists(outfile):
        return True
    # If flag is False but filesize of output is 0, also run
    elif not flag and not is_non_zero_file(outfile):
        return True
    # Otherwise, do not run
    else:
        return False