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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 context_list(zap_helper):
 """List the available contexts."""

    contexts = zap_helper.zap.context.context_list
    if len(contexts):
        console.info('Available contexts: {0}'.format(contexts[1:-1]))
    else:
        console.info('No contexts available in the current session')