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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 GetPlatformRestrictions(campaign_feed):
 """Get the Platform Restrictions for a given Campaign Feed. Args: campaign_feed: the Campaign Feed we are retrieving Platform Restrictons for. Returns: The Platform Restrictions for the given feed. """

  platform_restrictions = None

  if campaign_feed['matchingFunction']['operator'] == 'AND':
    for argument in campaign_feed['matchingFunction']['lhsOperand']:
      # Check if matchingFunction is EQUALS(CONTEXT.DEVICE, 'Mobile')
      if argument['value']['operator'] == 'EQUALS':
        request_context_operand = argument['value']['lhsOperand'][0]

        if (request_context_operand and
            request_context_operand == 'DEVICE_PLATFORM'):
                  # This needs to be capitalized for ExtensionSettingPlatform.
          platform_restrictions = argument['value']['rhsOperand'][0].upper()

  return platform_restrictions