01.py

print("Hello world!")

pi = 3.14159
radius = 2.2
# area of circle equation <- this is a comment
area = pi * (radius**2)
print(area)

# change values of radius <- another comment
# use comments to help others understand what you are doing in code
radius = radius + 1
print(area)  # area doesn't change
area = pi * (radius**2)
print(area)

#############################
#### COMMENTING LINES #######
#############################
# to comment MANY lines at a time, highlight all of them then CTRL+/ or CMD+/ on Mac
# do CTRL+/ or CMD+/ again to uncomment them
# try it on the next few lines below!

area = pi*(radius**2)
print(area)
radius = radius + 1
area = pi*(radius**2)
print(area)

#############################
#### AUTOCOMPLETE #######
#############################
# Repl.it can autocomplete names for you
# start typing a variable name defined in your program and hit tab
# before you finish typing -- try it below

# define a variable
a_very_long_variable_name_dont_name_them_this_long_pls = 0

# below, start typing a_ve then hit tab... cool, right!
# use autocomplete to change the value of that variable to 1

# use autocomplete to write a line that prints the value of that long variable
# notice that Repl.it also automatically adds the closed parentheses for you!