Move circulation functions to utils

They will also be used by the meta path algorithms too

src/pybel_tools/analysis/stability.py

@@ -366,24 +366,3 @@ def get_dampened_triplets(graph):
     :rtype: iter[tuple]
     """
     return _get_disregulated_triplets_helper(graph, CAUSAL_DECREASE_RELATIONS)
-
-
-def get_circulations(t):
-    """Iterate over all possible circulations of an ordered collection (tuple or list)
-
-    :param tuple or list t:
-    :rtype: iter
-    """
-    for i in range(len(t)):
-        yield t[i:] + t[:i]
-
-
-def canonical_circulation(t, key=None):
-    """Get get a canonical representation of the ordered collection by finding its minimum circulation with the
-    given sort key
-
-    :param tuple or list t:
-    :param key: A function for sort
-    :return: The
-    """
-    return min(get_circulations(t), key=key)

src/pybel_tools/utils.py

@@ -6,15 +6,15 @@
 import itertools as itt
 import json
 import logging
+import os
 import time
+from collections import Counter, defaultdict
 from itertools import zip_longest
+from operator import itemgetter
 
 import jinja2
 import networkx as nx
-import os
 import pandas as pd
-from collections import Counter, defaultdict
-from operator import itemgetter
 from pkg_resources import get_distribution
 
 from pybel.constants import (
@@ -472,3 +472,24 @@ def hash_str_to_int(hash_str, length=16):
     :rtype: int
     """
     return int(hash_str, 16) % (10 ** length)
+
+
+def get_circulations(t):
+    """Iterate over all possible circulations of an ordered collection (tuple or list)
+
+    :param tuple or list t:
+    :rtype: iter
+    """
+    for i in range(len(t)):
+        yield t[i:] + t[:i]
+
+
+def canonical_circulation(t, key=None):
+    """Get get a canonical representation of the ordered collection by finding its minimum circulation with the
+    given sort key
+
+    :param tuple or list t:
+    :param key: A function for sort
+    :return: The
+    """
+    return min(get_circulations(t), key=key)