added node_count. version bump

Author: Alessandro

Project.toml

@@ -1,7 +1,7 @@
 name = "TermInterface"
 uuid = "8ea1fca8-c5ef-4a55-8b96-4e9afe9c9a3c"
 authors = ["Shashi Gowda <gowda@mit.edu>", "Alessandro Cheli <sudo-woodo3@protonmail.com>"]
-version = "0.1.3"
+version = "0.1.4"
 
 [compat]
 julia = "1"

src/utils.jl

@@ -5,4 +5,11 @@ Returns a single argument anonymous function predicate, that returns `true` if a
 the argument to the predicate satisfies `isterm` and `gethead(x) == f` 
 """
 is_operation(f) = @nospecialize(x) -> isterm(x) && (gethead(x) == f)
-export is_operation
+export is_operation
+
+
+"""
+    node_count(t)
+Count the nodes in a symbolic expression tree satisfying `isterm` and `getargs`.
+"""
+node_count(t) = isterm(t) ? reduce(+, node_count(x) for x in  getargs(t), init=0) + 1 : 1