<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def replace_substitutes(string):
 	""" 	Return the given string with all known common substitutes replaced with 	their IPA-compliant counterparts. 	"""

	for non_ipa, ipa in chart.replacements.items():
		string = string.replace(non_ipa, ipa)

	return string