intro.md

+### Work with list objects in Python
+Assign an empty list to a variable **a**     
+```python
+a = []
+```
+
+Append the *float* object ```3.0``` to this list
+```python
+a.append(3.0)
+```
+
+This result is a list object **a** which has the length ```1``` and contains only the number ```3.0```
+