Function S2CellId.toString

Creates a human readable debug string. Used for << and available for direct usage as well. The format is "f/dd..d" where "f" is a digit in the range [0-5] representing the S2CellId face, and "dd..d" is a string of digits in the range [0-3] representing each child's position with respect to its parent. (Note that the latter string may be empty.)

For example "4/" represents S2CellId::FromFace(4), and "3/02" represents

S2CellId

:FromFace(3).child(0).child(2).