code: def _ema(series, periods: int, fillna: bool = False):
      min_periods = 0 if fillna else periods
      return series.ewm(
          span=periods, min_periods=min_periods, adjust=False
      ).mean()
  
file_path: ta/ta/utils.py
imports: import math
  import numpy
  import pandas
label_desc: Use image node_id 3 for calling a global function with example usage: _ema(series, periods, fillna) and returns: series