functions.py

# arguments can be of two types: with default values and without default values
# those with default values are called keyword arguments
# for eg the print function we use has 'sep' as a keyword argument which is '\n' by default

# below is also a way you can document your function using docstrings
def distance_travelled(t, u = 0, g = 9.81):
  """
  Function distance_travelled calculates the distance travelled by an object
  with initial speed u, in a time interval of t, where acceleration due to gravity is g

  input: t (time taken), u (initial speed) g (acceleration due to gravity)
  output: distance travelled

  Example: 
      >>> distance_travelled(1.0)

          4.905
  """
  d = u*t + 0.5 * g * t**2
  return d

print(distance_travelled(2.0))
print(distance_travelled(2.0, u = 1.0))
print(distance_travelled(2.0, g = 9.7))
print(distance_travelled(g = 9.7, t = 2.0))

# scope inside a function is different than the one outside it
# inside function scope, you can access the outer scope variables but cannot change them

def set_name(input_name):
  name = input_name
  print(f"Name inside the function: {name}")

set_name("Scaler")
# print(name) # NameError: this variable is not defined

""" 
# Exercise: What should be the output for this piece of code?
def add_char_to_list(char, lst = []):
  lst.append(char)
  return lst
add_char_to_list('s')
add_char_to_list('c')
add_char_to_list('a')
add_char_to_list('l')
add_char_to_list('e')
print(''.join(add_char_to_list('r')))
"""