code: def get_ccle_mutations(gene_list, cell_lines, mutation_type=None):
      
      mutations = {cl: {g: [] for g in gene_list} for cl in cell_lines}
      for cell_line in cell_lines:
          mutations_cl = get_mutations(ccle_study, gene_list,
                                       mutation_type=mutation_type,
                                       case_id=cell_line)
          for gene, aa_change in zip(mutations_cl['gene_symbol'],
                                     mutations_cl['amino_acid_change']):
              aa_change = str(aa_change)
              mutations[cell_line][gene].append(aa_change)
      return mutations
docs: Return a dict of mutations in given genes and cell lines from CCLE.
  
      This is a specialized call to get_mutations tailored to CCLE cell lines.
  
      Parameters
      ----------
      gene_list : list[str]
          A list of HGNC gene symbols to get mutations in
      cell_lines : list[str]
          A list of CCLE cell line names to get mutations for.
      mutation_type : Optional[str]
          The type of mutation to filter to.
          mutation_type can be one of: missense, nonsense, frame_shift_ins,
          frame_shift_del, splice_site
  
      Returns
      -------
      mutations : dict
          The result from cBioPortal as a dict in the format
          {cell_line : {gene : [mutation1, mutation2, ...] }}
  
          Example:
          {'LOXIMVI_SKIN': {'BRAF': ['V600E', 'I208V']},
          'SKMEL30_SKIN': {'BRAF': ['D287H', 'E275K']}}