copy = (out, line) => {
  out[0] = line[0]
  out[1] = line[1]
  out[2] = line[2]
  return out
}
Copy the given line to the receiving line.

@param {line2} out - receiving line
@param {line2} line - line to copy
@returns {line2} out
@alias module:modeling/maths/line2.copy