Add docstrings for additional methods in quantumlib#2480

Author: smitsanghavi

cirq/sim/clifford/clifford_simulator.py

@@ -254,9 +254,14 @@ def to_numpy(self):
         return self.ch_form.to_state_vector()
 
     def stabilizers(self) -> List[DensePauliString]:
+        """Returns the stabilizer generators of the state. These
+        are n operators {S_1,S_2,...,S_n} such that S_i |psi> = |psi> """
         return self.tableau.stabilizers()
 
     def destabilizers(self) -> List[DensePauliString]:
+        """Returns the destabilizer generators of the state. These
+        are n operators {S_1,S_2,...,S_n} such that along with the stabilizer
+        generators above generate the full Pauli group on n qubits."""
         return self.tableau.destabilizers()
 
     def wave_function(self):

cirq/sim/clifford/clifford_tableau.py

@@ -169,6 +169,11 @@ def g(x1, z1, x2, z2):
         self.zs[q1, :] ^= self.zs[q2, :]
 
     def _row_to_dense_pauli(self, i: int) -> DensePauliString:
+        """Returns a DensePauliString representing the row at index i in the
+        tableau. The length of the string is equal to the total number of
+        qubits and each character represents the effective single Pauli
+        operator on that qubit. The overall phase is captured in the
+        coefficient."""
         coefficient = -1 if self.rs[i] else 1
         pauli_mask = ""