```ruby
#
# concat.rb
#

module Puppet::Parser::Functions
  newfunction(:concat, :type => :rvalue, :doc => <<-EOS
Appends the contents of array 2 onto array 1.

*Example:*

    concat(['1','2','3'],['4','5','6'])

Would result in:

  ['1','2','3','4','5','6']
    EOS
  ) do |arguments|

    # Check that 2 arguments have been given ...
    raise(Puppet::ParseError, "concat(): Wrong number of arguments " +
      "given (#{arguments.size} for 2)") if arguments.size != 2

    a = arguments[0]
    b = arguments[1]

    # Check that the first parameter is an array
    unless a.is_a?(Array)
      raise(Puppet::ParseError, 'concat(): Requires array to work with')
    end

    if b.is_a?(Array)
      result = a.concat(b)
    else
      result = a << b
    end

    return result
  end
end

# vim: set ts=2 sw=2 et :
```

Concatenate arrays without modifying the first array
user
```ruby
#
# concat.rb
#

module Puppet::Parser::Functions
  newfunction(:concat, :type => :rvalue, :doc => <<-EOS
Appends the contents of array 2 onto array 1.

*Example:*

    concat(['1','2','3'],['4','5','6'])

Would result in:

  ['1','2','3','4','5','6']
    EOS
  ) do |arguments|

    # Check that 2 arguments have been given ...
    raise(Puppet::ParseError, "concat(): Wrong number of arguments " +
      "given (#{arguments.size} for 2)") if arguments.size != 2

    a = arguments[0]
    b = arguments[1]

    # Check that the first parameter is an array
    unless a.is_a?(Array)
      raise(Puppet::ParseError, 'concat(): Requires array to work with')
    end

    result = a + Array(b)

    return result
  end
end

# vim: set ts=2 sw=2 et :
```
assistant