chore: supplement signature comments

Co-authored-by: niupilot[bot] <230321281+niupilot[bot]@users.noreply.github.com>
Signed-off-by: Micro Liu <858039956@qq.com>

Author: 2 people

symbol/symbol.go

@@ -1,5 +1,23 @@
 package symbol
 
+// represents the origin of a function signature
+type SigSource int
+
+const (
+	// signature extracted from docstring
+	SigSourceDoc SigSource = iota
+	// signature from Python inspect module
+	SigSourceInspect
+	// generic fallback signature
+	SigSourceParadigm
+)
+
+// represents a function signature with its source information
+type Signature struct {
+	Str    string    `json:"str"`    // The signature string
+	Source SigSource `json:"source"` // Where the signature was obtained
+}
+
 type Symbol struct {
 	Name string    `json:"name"`
 	Type string    `json:"type"`
@@ -12,16 +30,3 @@ type Module struct {
 	Functions []*Symbol `json:"functions"` // package functions
 	// TODO: variables, classes, etc.
 }
-
-type SigSource int
-
-const (
-	SigSourceDoc SigSource = iota
-	SigSourceInspect
-	SigSourceParadigm
-)
-
-type Signature struct {
-	Str    string    `json:"str"`
-	Source SigSource `json:"source"`
-}