Example code still uses deprecated argument "code_mapping"

[chpark-vuno]

In the example code for MIMIC3Dataset, the argument code_mapping is still shown.
However, in the current version of the codebase, code_mapping is no longer a valid argument (deprecated/removed).

PyHealth/examples/mortality_mimic3_tcn.py

Lines 9 to 15 in b36399c

	base_dataset = MIMIC3Dataset(
	root="/srv/local/data/physionet.org/files/mimiciii/1.4",
	tables=["DIAGNOSES_ICD", "PROCEDURES_ICD", "PRESCRIPTIONS"],
	code_mapping={"ICD9CM": "CCSCM", "ICD9PROC": "CCSPROC", "NDC": "ATC"},
	dev=False,
	refresh_cache=False,
	)

[jhnwu3]

yeah, sorry that's a pyhealth 1.6 API. A lot of the datasets have been completely revamped in what we're going to call pyhealth 2.0a