DOC: minor typo

Author: yarikoptic

nibabel/volumeutils.py

@@ -97,7 +97,7 @@ def __init__(self, codes, fields=('code',), map_maker=dict):
 
         Parameters
         ----------
-        codes : seqence of sequences
+        codes : sequence of sequences
             Each sequence defines values (codes) that are equivalent
         fields : {('code',) string sequence}, optional
             names by which elements in sequences can be accessed