Suggestion for cells_prefix parameter

[ppKrauss]

Perhaps it is a suggestion also to add a little helper-method at Python's lib... The motivation was the interface at s2.sidewalklabs.com/regioncoverer.

The use of cell-prefix is interesting

• to reduce the string length of a list of cell-IDs at interface;
• to express "area code" (the prefix) and its "local addresses" (the cells) representation.

Example of an ordinary list of cells by full strings: cells=94ce58ad, 94ce58b3, 94ce5f15, 94ce5f35fc, 94ce5f37, 94ce5f3c, 94ce5f5, 94ce5f67c, 94ce5f69, 94ce5f6b.

Using prefix:

1. For simple string compression: cells_prefix=94ce5&cells=8ad,8b3,f15,f35fc,f37,f3c,f5,f67c,f69,f6b.

2. For "area code" and its local-address-cells: cells_prefix=94ce5&cells=8ad1,8ad21,f35fc,f371,f37a .