We will look at an example of adding two numbers using TensorFlow. A placeholder is a node in a TensorFlow graph to which values can be passed during a session. A session is when the graph is initialized and ready to process the values:

1. We will define two placeholders to take two integer values:

a = tf.Placeholder(tf.int32)
b = tf.Placeholder(tf.int32)

2. Add these two variables and store them in a variable:

c = a + b

3. A dictionary of values is created to load to the placeholders. The keys are variables with placeholders themselves, as shown here:

values = {a: 5, b: 3}

4. Create a session. Once a session is initialized, the graph is loaded into the memory and is ready for the consumption of values into placeholders, and to do the processing:

sess = tf.Session()

5. Run the session by passing values into the graph. The output from the c node is requested back, so use the following code:

print(sess.run([c], values))

The output should be [8.0]. This example illustrates how values can be fed into the graph and processed.