{"$schema":"urn:prism:schema:v1:spec",
 "title":"Legend layout — horizontal, shaped swatches",
 "data":{"values":[
   {"month":"Jan","channel":"Direct","signups":30},
   {"month":"Jan","channel":"Referral","signups":18},
   {"month":"Feb","channel":"Direct","signups":42},
   {"month":"Feb","channel":"Referral","signups":26}]},
 "mark":{"type":"point","size":90},
 "encoding":{
   "x":{"field":"month","type":"nominal"},
   "y":{"field":"signups","type":"quantitative"},
   "color":{"field":"channel","type":"nominal",
     "legend":{"orient":"bottom","direction":"horizontal","symbol_type":"square","symbol_size":14}}}}