Add helpers to identify line types in the saved session files

src/helpers/line_type.zsh

@@ -0,0 +1,18 @@
+# ------------------------------------------------------------------------------
+# When dumping windows and panes, the line type is prepended to each line
+# These functions help identify the type of a line
+
+function __tsm::helpers::is_line_type() {
+  local line_type="$1" line="$2"
+  [[ "$line" =~ "^$line_type" ]]
+}
+
+function __tsm::helpers::is_line_type::pane() {
+  __tsm::helpers::is_line_type "pane" "$1"
+}
+
+function __tsm::helpers::is_line_type::window() {
+  __tsm::helpers::is_line_type "window" "$1"
+}
+
+# ------------------------------------------------------------------------------