Create Segment
Create a new segment. A segment defines a part of the population of an
entity, for example, the population of users. It contains an overall
proportion of the population as well as optional targeting criteria, like
the country a user is from. A segment can also be coordinated with other
segments, by setting exclusivity_tags and exclusive_to, preventing one
user to be included in two segments, that are exclusive to each other,
simultaneously.
Note, the segment is not active until it is allocated.

