What is `/bin/xhere` in Cygwin?

It is a part of chere.

https://github.com/mirror/chere/blob/6dfd88bd/src/xhere#L33-L78

As I understand, xhere enables Unix commands.
Without xhere Cygwin is unable to find Unix commands.
See the example below:
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As I understand, the same effect can be achieved by starting bash with the --login option:

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What are Bash startup files?