It looks like you are creating another range with values from a to (map, map_function) inclusive. You start by proposing a transformation operator, then you give an example using a hypothetical range operator a = (1..10) which has no transformation.
While pipelining is a transformation operation, range is not.
Common characters used for the pipe operator are | and |>. For ranges, common characters are .. and :.
Python already supports the : range operator, while the pipe operator is supported in another Python compiler. You can learn more about it here. You might want to try it out and see what you think.