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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 is_file(package):
 """Determine if a package name is for a File dependency."""

    if hasattr(package, "keys"):
        return any(key for key in package.keys() if key in ["file", "path"])

    if os.path.exists(str(package)):
        return True

    for start in SCHEME_LIST:
        if str(package).startswith(start):
            return True

    return False