new_contents: """Structure prediction implementation."""
  
  from typing import Generator, List, Tuple, Optional
  
  from .database import StructureDB
  from .mutation import CationMutator
  from .structure import SmactStructure
  
  
  class StructurePredictor:
      """Provides structure prediction functionality.
  
      Implements a statistically-based model for determining
      likely structures of a given composition, based on a
      database of known compositions and a lambda table of
      weights.
  
      Based on the algorithm presented in:
          Hautier, G., Fischer, C., Ehrlacher, V., Jain, A., and Ceder, G. (2011)
          Data Mined Ionic Substitutions for the Discovery of New Compounds.
          Inorganic Chemistry, 50(2), 656-663.
          `doi:10.1021/ic102031h <https://pubs.acs.org/doi/10.1021/ic102031h>`_
  
      """
  
      def __init__(self, mutator: CationMutator, struct_db: StructureDB):
          """Initialize class."""
          self.cm = mutator
          self.db = struct_db
  
      def predict_structs(
        self,
        species: List[Tuple[str, int]],
        thresh: Optional[float] = 1e-3, ) -> Generator[Tuple[SmactStructure, float], None, None]:
          """Predict structures for a combination of species.
  
          Args:
              species: A list of (element, charge). The constituent species
                  of the target compound.
              thresh: The probability threshold, below which to discard
                  predictions.
  
          Yields:
              Potential structures, as tuples of (structure, probability).
  
          """
          raise NotImplementedError
  
subject: Structure prediction boilerplate