Implement remaining command_... functions for control structures

lambdaV.py

@@ -173,12 +173,28 @@ def command_take():
     return ""
 
 def command_repeat(number, parsed_code):
+    for i in range(number):
+        result = run_code(parsed_code)
+        if not result=="":
+            return result
     return ""
 
 def command_while(parsed_condition, parsed_code):
+    while parsed_condition[0](parsed_condition[1]):
+        result = run_code(parsed_code)
+        if not result=="":
+            return result
     return ""
 
 def command_if(parsed_condition, parsed_then_code, parsed_else_code):
+    if parsed_condition[0](parsed_condition[1]):
+        result = run_code(parsed_then_code)
+        if not result=="":
+            return result
+    elif not parsed_else_code==None:
+        result = run_code(parsed_else_code)
+        if not result=="":
+            return result
     return ""