Unicode.Property.emoji_modifier_base
You're seeing just the function
emoji_modifier_base, go back to Unicode.Property module for more information.
Returns :emoji_modifier_base or nil indicating
if the codepoint or string has the property
:emoji_modifier_base.
For string parameters, all codepoints in
the string must have the :emoji_modifier_base
property in order for the result to :emoji_modifier_base.