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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 requirements(section=None):
 """Helper for loading dependencies from requirements files."""

    if section is None:
        filename = "requirements.txt"
    else:
        filename = f"requirements-{section}.txt"

    with open(filename) as file:
        return [line.strip() for line in file]