module KindHelper

base(). @description

Predicate. Verifies the kind is 'base'. A 'base' Node is a Node bearing
no backward attachment and a forward attachment.

@return [TrueClass, FalseClass]

True in the case 'back' is nil and 'front' refers a Node. False otherwise.

# File lib/helpers/kind_helper.rb, line 55
def base()
  return (!back_attached() && front_attached())
end

common(). @description

Predicate. Verifies the kind is common. A 'common' Node is a fully
attached Node.

@return [TrueClass, FalseClass]

True in the case both 'back' and 'front' refer Nodes.

# File lib/helpers/kind_helper.rb, line 45
def common()
  return (back_attached() && front_attached())
end

kind(). @description

Discerns the kind. The kind is either 'base', 'common', 'lone', or
'pioneer'.

@return [String]

A kind String.

# File lib/helpers/kind_helper.rb, line 15
def kind()
  case
  when lone()
    return 'lone'.freeze()
  when common()
    return 'common'.freeze()
  when base()
    return 'base'.freeze()
  when pioneer()
    return 'pioneer'.freeze()
  end
end

lone(). @description

Predicate. Verifies the kind is lone. A 'lone' Node is a Node bearing
no attachments.

@return [TrueClass, FalseClass]

True in the case self's 'back' reference and self's 'front' reference
are nil. False otherwise.

# File lib/helpers/kind_helper.rb, line 35
def lone()
  return no_attachments()
end

pioneer(). @description

Predicate. Verifies self's kind is 'pioneer'. A 'pioneer' Node is a
Node bearing a 'back' attachment and no 'front' attachment.

@return [TrueClass, FalseClass]

True in the case self's 'back' reference is a Node and self's 'front'
reference is nil. False otherwise.

# File lib/helpers/kind_helper.rb, line 66
def pioneer()
  return (back_attached() && !front_attached())
end