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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 pip_install_requirements(requirements, constraints=None, **options):
 """Install a requirements file. :param constraints: Path to pip constraints file. http://pip.readthedocs.org/en/stable/user_guide/#constraints-files """

    command = ["install"]

    available_options = ('proxy', 'src', 'log', )
    for option in parse_options(options, available_options):
        command.append(option)

    command.append("-r {0}".format(requirements))
    if constraints:
        command.append("-c {0}".format(constraints))
        log("Installing from file: {} with constraints {} "
            "and options: {}".format(requirements, constraints, command))
    else:
        log("Installing from file: {} with options: {}".format(requirements,
                                                               command))
    pip_execute(command)