Python list in psql query as a parameter

Question

I tried the following code in order to run my query using hadm list inside the query but at the end.

hadm = [1,2,3,4,5,6,7,8,9]
placeholder= '?'
placeholders= ','.join(placeholder for unused in hadm)

sql_lab = """SELECT admissions.hadm_id as hadm_id, min(charttime) as first_lab
FROM mimic2v26.labevents JOIN mimic2v26.admissions using(subject_id) 
WHERE admissions.hadm_id in (%s) AND
charttime - admit_dt > interval '-48 hours'
GROUP BY admissions.hadm_id"""%placeholders

cur.execute(sql_lab,hadm)

I got the following error:

ProgrammingError                          Traceback (most recent call last)
<ipython-input-156-2263cc2076d2> in <module>()
      7 charttime - admit_dt > interval '-48 hours'
      8 GROUP BY admissions.hadm_id"""%placeholders
----> 9 cur.execute(sql_lab,hadm)

ProgrammingError: syntax error at or near ","
LINE 3: WHERE admissions.hadm_id in (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?...
                                  ^