code: def log(ctx, x, b=None):
      if b is None:
          return ctx.ln(x)
      wp = ctx.prec + 20
      return ctx.ln(x, prec=wp) / ctx.ln(b, prec=wp)
  
imports: from ..libmp.backend import xrange
  import math
  import cmath
label_desc: Use image node_id 33 for calling a global function with example usage: log(ctx, x, b) and returns: unknown, ctx