# File sample/psql.rb, line 309
def unescape(source)
  dest = source.gsub(/(\\n|\\r|\\t|\\f|\\\\)/) {
    |c|
    case c
    when "\\n"
      "\n"
    when "\\r"
      "\r"
    when "\\t"
      "\t"
    when "\\f"
      "\f"
    when "\\\\"
      "\\"
    end
  }
  return dest
end