imperative docstrings

src/y0/hierarchical.py

@@ -21,7 +21,7 @@
     "collapse_HCM"]
 
 def HCM_from_lists(*, obs_subunits=[], unobs_subunits=[], obs_units=[], unobs_units=[], edges=[]):
-    """Creates a hierarchical causal model from the given node and edge lists.
+    """Create a hierarchical causal model from the given node and edge lists.
 
     :param obs_subunits: a list of names for the observed subunit variables
     :param unobs_subunits: a list of names for the unobserved subunit variables
@@ -41,7 +41,7 @@ def HCM_from_lists(*, obs_subunits=[], unobs_subunits=[], obs_units=[], unobs_un
     return HCM
 
 def get_observed(HCM):
-    """Returns the set of observed variables (both unit and subunit) in the HCM."""
+    """Return the set of observed variables (both unit and subunit) in the HCM."""
     observed_nodes = set()
     for node_name in HCM.nodes():
         node = HCM.get_node(node_name)
@@ -50,33 +50,33 @@ def get_observed(HCM):
     return observed_nodes
 
 def get_unobserved(HCM):
-    """Returns the set of unobserved variables (both unit and subunit) in the HCM."""
+    """Return the set of unobserved variables (both unit and subunit) in the HCM."""
     all_nodes = set(HCM.nodes())
     return all_nodes - get_observed(HCM)
 
 def get_subunits(HCM):
-    """Returns the set of subunit variables in the HCM."""
+    """Return the set of subunit variables in the HCM."""
     return set(HCM.get_subgraph('cluster_subunits').nodes())
 
 def get_units(HCM):
-    """Returns the set of unit variables in the HCM."""
+    """Return the set of unit variables in the HCM."""
     subunits = get_subunits(HCM)
     return set(HCM.nodes()) - subunits
 
 def parents(HCM, node):
-    """Returns the set of parent/predecessor variables of the given variable in the HCM."""
+    """Return the set of parent/predecessor variables of the given variable in the HCM."""
     parents = set(HCM.predecessors(node))
     return parents
 
 def _node_string(nodes):
-    """Returns a formated string for use in creating Q variables for collapsed HCMs."""
+    """Return a formated string for use in creating Q variables for collapsed HCMs."""
     s = ""
     for node in nodes:
         s += node.get_name().lower() + ","
     return s[: -1]
 
 def create_Qvar(HCM, subunit_node):
-    """Returns a y0 Variable for the unit-level Q variable of the given subunit variable in the HCM."""
+    """Return a y0 Variable for the unit-level Q variable of the given subunit variable in the HCM."""
     subunit_parents = parents(HCM, subunit_node) & get_subunits(HCM)
     parent_str = _node_string(subunit_parents)
     if parent_str == '':
@@ -86,7 +86,7 @@ def create_Qvar(HCM, subunit_node):
     return Variable(Q_str)
 
 def direct_unit_descendents(HCM, subunit_node):
-    """Returns the set of direct unit descendents of the given subunit variable in the HCM."""
+    """Return the set of direct unit descendents of the given subunit variable in the HCM."""
     units = get_units(HCM)
     subunits = get_subunits(HCM)
     descendents = HCM.successors(subunit_node)
@@ -112,8 +112,8 @@ def direct_unit_descendents(HCM, subunit_node):
     return duds
 
 def collapse_HCM(HCM):
-    """Returns a collapsed hierarchical causal model.
-    
+    """Return a collapsed hierarchical causal model.
+
     :param HCM: pygraphviz AGraph of the hierarchical causal model to be collapsed
     :returns: NxMixedGraph
     """