code: public static String color(FunctionEnum fe) {
          if (fe == null) {
              return DFLT_NODE_COLOR;
          }
          switch (fe) {
          case ABUNDANCE:
              return "40,255,85";
          case BIOLOGICAL_PROCESS:
              return "255,51,102";
          case CATALYTIC_ACTIVITY:
              return "100,100,255";
          case CELL_SECRETION:
              return "204,204,255";
          case CELL_SURFACE_EXPRESSION:
              return "204,204,255";
          case CHAPERONE_ACTIVITY:
              return "100,100,255";
          case COMPLEX_ABUNDANCE:
              return "102,153,255";
          case COMPOSITE_ABUNDANCE:
              return "222,255,255";
          case DEGRADATION:
              return "255,51,102";
          case GENE_ABUNDANCE:
              return "204,255,204";
          case GTP_BOUND_ACTIVITY:
              return "100,100,255";
          case KINASE_ACTIVITY:
              return "100,100,255";
          case MICRORNA_ABUNDANCE:
              return "0,255,150";
          case MOLECULAR_ACTIVITY:
              return "100,100,255";
          case PATHOLOGY:
              return "255,51,102";
          case PEPTIDASE_ACTIVITY:
              return "100,100,255";
          case PHOSPHATASE_ACTIVITY:
              return "100,100,255";
          case PROTEIN_ABUNDANCE:
              return "85,255,255";
          case REACTION:
              return "255,51,102";
          case RIBOSYLATION_ACTIVITY:
              return "100,100,255";
          case RNA_ABUNDANCE:
              return "40,255,85";
          case TRANSCRIPTIONAL_ACTIVITY:
              return "100,100,255";
          case TRANSPORT_ACTIVITY:
              return "100,100,255";
          }
          return DFLT_NODE_COLOR;
      }
docs: Returns an RGB tuple of the form {@code "x,x,x"} for the supplied
  {@link FunctionEnum}. Defaults to gray; RGB {@code "150,150,150"}.
  
  @param fe {@link FunctionEnum}
  @return Non-null {@link String}