Returns a copy of +self+, left-justified and, if necessary, right-padded with the +pad_string+:

  'hello'.ljust(10)       # => "hello     "
  '  hello'.ljust(10)     # => "  hello   "
  'hello'.ljust(10, 'ab') # => "helloababa"
  'こんにちは'.ljust(10)   # => "こんにちは     "

If <tt>width <= self.length</tt>, returns a copy of +self+:

  'hello'.ljust(5)  # => "hello"
  'hello'.ljust(1)  # => "hello"  # Does not truncate to width.

Related: see {Converting to New String}[rdoc-ref:String@Converting+to+New+String].
