fix and add some functions

bbp_ng/UTIL_functions.py

@@ -1,4 +1,4 @@
-import math
+import math, typing
 
 class BBPException(Exception):
     """
@@ -36,3 +36,20 @@ def clamp_int(v: int, min_val: int, max_val: int) -> int:
     elif (v > max_val): return max_val
     else: return v
 
+
+_TLimitIterator = typing.TypeVar('_TLimitIterator')
+def limit_iterator(it: typing.Iterator[_TLimitIterator], limit_count: int) -> typing.Iterator[_TLimitIterator]:
+    """!
+    A generator wrapper for another generator to make sure the length of the given generator output entries 
+    is not greater (<= less equal) than given number.
+
+    @param it[in] A iterator need to be limited. Use iter(ls) if your passing value is not a generator (eg. tuple, list)
+    @param limit_count[in] The count to limit. Must be a positive number. Can be 0.
+    @return A generator with limited length. Use tuple(ret) if you just want to convert it to a tuple.
+    """
+    counter: int = 0
+    while counter < limit_count:
+        # if no elements in given iterator, StopIteration will raise. 
+        # It is okey because it naturally stop the iteration of this generator.
+        yield next(it)
+        counter += 1