Get top coins by 24 hour trading volume value in the requested currency.
	
	Args:
		tsym: TO symbol.
		limit: Number of results. Default value returns top 20 coins.
	
	Returns:
		Function returns a list containing a dictionary for each result:

		[{'SUPPLY': ..., 'SYMBOL': ..., 'VOLUME24HOURTO': ...}, 
		 {...}, 
		 ...]

		The list is ordered based on the volume of the TO currency starting with 
		the highest value.

def get_top_coins(tsym, limit=20):
	"""Get top coins by 24 hour trading volume value in the requested currency.
	
	Args:
		tsym: TO symbol.
		limit: Number of results. Default value returns top 20 coins.
	
	Returns:
		Function returns a list containing a dictionary for each result:

		[{'SUPPLY': ..., 'SYMBOL': ..., 'VOLUME24HOURTO': ...}, 
		 {...}, 
		 ...]

		The list is ordered based on the volume of the TO currency starting with 
		the highest value.
	"""
	
	# load data
	url = build_url('volumes', tsym=tsym, limit=limit)
	data = load_data(url)

	return data['Data']