docs: def increase_volume(percentage):
  	'''Increase the volume.
  
  	Increase the volume by a given percentage.
  
  	Args:
  			percentage (int): The percentage (as an integer between 0 and 100) to increase the volume by.
  
  	Raises:
  			ValueError: if the percentage is >100 or <0.
  	'''
  
  	if percentage > 100 or percentage < 0:
  		raise ValueError('percentage must be an integer between 0 and 100')
  
  	if system.get_name() == 'windows':
  		# TODO: Implement volume for Windows. Looks like WinAPI is the
  		# solution...
  		pass
  
  	elif system.get_name() == 'mac':
  		volume_int = percentage / 10
  		old_volume = get()
  
  		new_volume = old_volume + volume_int
  
  		if new_volume > 10:
  			new_volume = 10
  
  		set_volume(new_volume * 10)
  
  	else:
  		# Linux/Unix
  		formatted = '%d%%+' % percentage
  		# + or - increases/decreases in amixer
  
  		sp.Popen(['amixer', '--quiet', 'sset', 'Master', formatted]).wait()