Description of Double hasing

data_structures/hashing/double_hash.py

@@ -1,4 +1,25 @@
 #!/usr/bin/env python3
+"""
+Double hashing is a collision resolving technique in 
+Open Addressed Hash tables. Double hashing uses the idea of 
+applying a second hash function to key when a collision occurs.
+
+Advantages of Double hashing
+
+The advantage of Double hashing is that it is one of the best form of 
+probing, producing a uniform distribution of records throughout a hash table.
+This technique does not yield any clusters.
+It is one of effective method for resolving collisions.
+
+Double hashing can be done using : 
+(hash1(key) + i * hash2(key)) % TABLE_SIZE 
+
+Here hash1() and hash2() are hash functions and TABLE_SIZE 
+
+is size of hash table. 
+
+Reference: https://en.wikipedia.org/wiki/Double_hashing#:~:text=Double%20hashing%20is%20a%20computer,data%20structure%20on%20a%20table%20.
+"""
 from .hash_table import HashTable
 from .number_theory.prime_numbers import is_prime, next_prime