fixed similarterm

Author: Alessandro

src/TermInterface.jl

@@ -87,7 +87,8 @@ with `head` as the head and `args` as the arguments, `type` as the symtype
 and `metadata` as the metadata. By default this will execute `head(args...)`.
 `x` parameter can also be a `Type`.
 """
-similarterm(x, head, args; type=nothing, metadata=nothing) = head(args...)
+similarterm(x, head, args; type=nothing, metadata=nothing) = 
+    similarterm(typeof(x), head, args; type=type, metadata=nothing)
 similarterm(x::Type{Expr}, head, args; type=nothing, metadata=nothing) = Expr(head, args...)
 function similarterm(x::Type{T}, head::T, args; type=nothing, metadata=nothing) where T
     if !isterm(T) head else head(args...) end