instruction: what were the top four most frequent procedures that patients took in the same month after receiving open liver biopsy?
response: SELECT d_icd_procedures.short_title FROM d_icd_procedures WHERE d_icd_procedures.icd9_code IN (SELECT t3.icd9_code FROM (SELECT t2.icd9_code, DENSE_RANK() OVER (ORDER BY COUNT(*) DESC) AS c1 FROM (SELECT admissions.subject_id, procedures_icd.charttime FROM procedures_icd JOIN admissions ON procedures_icd.hadm_id = admissions.hadm_id WHERE procedures_icd.icd9_code = (SELECT d_icd_procedures.icd9_code FROM d_icd_procedures WHERE d_icd_procedures.short_title = 'open liver biopsy')) AS t1 JOIN (SELECT admissions.subject_id, procedures_icd.icd9_code, procedures_icd.charttime FROM procedures_icd JOIN admissions ON procedures_icd.hadm_id = admissions.hadm_id) AS t2 ON t1.subject_id = t2.subject_id WHERE t1.charttime < t2.charttime AND DATETIME(t1.charttime, 'start of month') = DATETIME(t2.charttime, 'start of month') GROUP BY t2.icd9_code) AS t3 WHERE t3.c1 <= 4)