diff --git a/src/caosadvancedtools/table_importer.py b/src/caosadvancedtools/table_importer.py
index 54fb61bb05da0aeebf5a1da5ff46a9443e59112d..15fb89af503e108aed2343e3d50838b797e31369 100755
--- a/src/caosadvancedtools/table_importer.py
+++ b/src/caosadvancedtools/table_importer.py
@@ -146,6 +146,29 @@ def win_path_converter(val):
 
 
 def enum_converter(val, options, ignore_case=True):
+    """Return the given value if it is contained in options, raise an
+    error otherwise.
+
+    Parameters
+    ----------
+    val : str
+        String value to be checked.
+    options : list<str>
+        List of possible values that val may obtain
+    ignore_case : bool, optional
+        Specify whether the comparison of val and the possible options
+        should ignor capitalization. Default is True.
+
+    Returns
+    -------
+    val : str
+       The original value if it is contained in options
+
+    Raises
+    ------
+    ValueError
+       If val is not contained in options.
+    """
     if ignore_case:
         val = val.lower()
         options = [o.lower() for o in options]
@@ -158,6 +181,7 @@ def enum_converter(val, options, ignore_case=True):
 
     return val
 
+
 class TSVImporter(object):
     def __init__(self, converters, obligatory_columns=[], unique_columns=[]):
         raise NotImplementedError()