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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 _build_vars_dict(vars_file='', variables=None):
 """Merge variables into a single dictionary Applies to CLI provided variables only """

    repex_vars = {}
    if vars_file:
        with open(vars_file) as varsfile:
            repex_vars = yaml.safe_load(varsfile.read())
    for var in variables:
        key, value = var.split('=')
        repex_vars.update({str(key): str(value)})
    return repex_vars