Python primer to revise Python language elements.

# This is basic Python primer program that will be used to understand
# language’s basic elements and structures.
# INDENTATION

for i in range(5):
  print(i)
print('done')

for i in range(5):
  print(i)
  print('done')

# Strings

print('this is string');
print("this is also string");

# Variable
var1=10;
var2='ten';

#comment single line
""" this is

multi line
comment
"""

#printing
print('Hello World');
print('Value is ', var1);
print('Value is ', var2);

# data structures
#dictionary -- associative array
a2 = {'one':1, 'two':2, 'three':3}

# lists -- ordered arrays
a3=[101,4,7,50,32]

# lists can be accessed via index.
print(a3[0]);
print(a3[-1]);
print(a3[3]);
print(a3[4]);
print(a3[3:5]);
print(a3);

#tuples like lists but they cannot be changed once created. they are creared with parenthesis.
a4=(3,7,10);

# individual values in tuple can be assigned to variables like :
v1,v2,v3=a4

print('v1=', v1);
print('v2=', v2);
print('v3=', v3);

# The value in a single entry tuple like "(13,)" can be assigned to a variable by putting a comma
# after the variable name like:
v1,=(13,)

#if the assignment is
v1=(13,)
print(v1);

# then v1 will contain the whole tuple"(13,)"

### Objects

# Everything in python is an object. as a3 list we have before, that is an object.
print(a3);
a3.append(25);
print(a3);

# Flow control if-elif-else statement, "or" "and", "=="
v=1
if v == 2 or v == 4:
  print('Even')
elif v == 1 or v == 3:
  print('odd')
else:
  print('Unknown Number')

##Loops
for i in range(10):
  print(i)
a5=['Aa', 'Bb', 'Cc']
for c in a5:
  print(c)

## functions, Functions may or may not return values.
#A function may be defined as:
def myfunc(p1, p2):
  "Hello : add two numbers"
  print(p1, p2)
  return p1 + p2
v10=myfunc(10,2)
print(v10)

#Functions are also objects and have attributes.
#The inbuilt __doc__ attribute can be used to find the function description:
print(myfunc.__doc__)

#Modules
#Sub-files can be included in Python scripts with an import statement.
#Many predefined modules exist, such as the os and the sys modules.

import os
import sys