For Redy@thautwarm

match_expr.jl

function emmmm(expr, guard)
    @match expr begin
       :(function $_(a, b, $(_...), $last)
           $(block...) end) 
        where guard(last) => (last, block)
    end
end

head = x->x[1]

guard = islowercase ∘ head ∘ string

emmmm(
    :(function f(a, b, c, d, e)_
         print(e)
      end), 
     guard)

# => 
# (:e, Any[:(#= REPL[17]:1 =#), :_, :(#= REPL[17]:2 =#), :(print(e))])