# File lib/fog/aws/requests/lambda/add_permission.rb, line 20
        def add_permission(params={})
          function_name  = params.delete('FunctionName')
          action         = params.delete('Action')
          principal      = params.delete('Principal')
          source_account = params.delete('SourceAccount')
          source_arn     = params.delete('SourceArn')
          sid            = params.delete('StatementId')

          permission = {
            'Action'      => action,
            'Principal'   => principal,
            'StatementId' => sid
          }
          permission['SourceAccount'] = source_account if source_account
          permission['SourceArn']     = source_arn     if source_arn

          request({
            :method  => 'POST',
            :path    => "/functions/#{function_name}/versions/HEAD/policy",
            :expects => 201,
            :body    => Fog::JSON.encode(permission),
            :parser  => Fog::AWS::Parsers::Lambda::Base.new
          }.merge(params))
        end