Open subset of possibly equal to

[kauesena]

Though there is a "open subset of" symbol, there is no "proper open subset of or equal to" symbol. For ⫏ ⫐, there are the counterparts ⫑ ⫒. For ⟃ ⟄, there are not. Also, perhaps it would be nice to have negated versions to mean properly contained open subset and properly contained closed set.

[xsrvmy]

I'm assuming there just isn't a unicode character for it? This package doesn't add any new unicode characters.