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