class_docstr: Context for fast low-precision arithmetic (53-bit precision, giving at most
  about 15-digit accuracy), using Python's builtin float and complex.
code: def psi(ctx, m, z):
      m = int(m)
      if m == 0:
          return ctx.digamma(z)
      return (-1) ** (m + 1) * ctx.fac(m) * ctx.zeta(m + 1, z)
  
imports: from .ctx_base import StandardBaseContext
  import math
  import cmath
  from .None import math2
  from .None import function_docs
  from .libmp import mpf_bernoulli, to_float, int_types
  from .None import libmp
label_desc: Use image node_id 25 for calling the FPContext obj's underlying member method code with example usage: obj.psi(ctx, m, z) and returns: unknown, ctx