code: def __str__(self):
      field_list = []
      for k, v in sorted(self.__dict__.items()):
          if v is None or isinstance(v, (float, int)):
              field_list.append("%s=%s" % (k, v))
          elif isinstance(v, str):
              field_list.append("%s='%s'" % (k, v))
      return "%s(%s)" % (self.__class__.__name__, ", ".join(field_list))
  
file_path: fancyimpute/fancyimpute/solver.py
imports: import warnings
  import numpy
  from sklearn.utils import check_array
  from .common import generate_random_column_samples
label_desc: Use image node_id 3 for calling the Solver obj's underlying member method code with example usage: obj.__str__() and returns: unknown