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