Prohibited pure escort tours from having an external destination

src/asim/configs/resident/external_non_mandatory_identification.csv

@@ -12,6 +12,7 @@ util_inc_15_50,Income 15 to 50k,"@np.where((df['income']>=15000) * (df['income']
 util_inc_100_250,Income 100k to 250k,"@np.where((df['income']>=100000) * (df['income']<=249999),1,0)",coef_income_100_250,
 util_inc_250plus,Income 250k plus,"@np.where(df['income']>=250000,1,0)",coef_income_250_plus,
 util_autos_0,0 auto household,"@np.where(df.auto_ownership==0,1,0)",coef_autos_0,
+util_is_pure_escort,Pure escort tours cannot have an external destination,"@np.where((df.school_esc_outbound == 'pure_escort')|(df.school_esc_inbound == 'pure_escort')))",-999,
 util_global_switch,Global switch to have everything internal,@NO_EXTERNAL,-999,
 util_dist_lt_2p5,Distance less than 2.5 miles,"@np.where(df.dist_to_external_zone<2.5,1,0)",coef_dist_lt_2p5,
 util_calibration,,1,0.43,