mh-assoc-string
    
    mh-assoc-string is an alias for `
assoc-string' in `
mh-compat.el'.
(mh-assoc-string 
KEY LIST &optional 
CASE-FOLD)
Like `assoc' but specifically for strings (and symbols).
This returns the first element of 
LIST whose car matches the string or
symbol 
KEY, or nil if no match exists.  When performing the
comparison, symbols are first converted to strings, and unibyte
strings to multibyte.  If the optional arg 
CASE-FOLD is non-nil, case
is ignored.
Unlike `assoc', 
KEY can also match an entry in 
LIST consisting of a
single string, rather than a cons cell whose car is a string.