Given a reaction and a known amount (moles or grams) of one species, compute the amount of

[
  {
    "scheme": "exact",
    "network": "eip155:8453",
    "payTo": "0xb3f4de103F34b99f0Da19B4F16D6B53a14C2194A",
    "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
    "amount": "4000",
    "maxTimeoutSeconds": 300
  }
]

{
  "bazaar": {
    "info": {
      "input": {
        "body": {
          "equation": "example",
          "given": {
            "amount": 1,
            "species": "example",
            "unit": "mol"
          },
          "target": "example",
          "targetUnit": "mol"
        },
        "bodyType": "json",
        "method": "POST",
        "type": "http"
      }
    },
    "schema": {
      "$schema": "https://json-schema.org/draft/2020-12/schema",
      "properties": {
        "input": {
          "additionalProperties": false,
          "properties": {
            "body": {
              "additionalProperties": false,
              "properties": {
                "equation": {
                  "description": "Reaction, e.g. \"H2 + O2 -> H2O\".",
                  "minLength": 1,
                  "type": "string"
                },
                "given": {
                  "additionalProperties": false,
                  "properties": {
                    "amount": {
                      "description": "Known amount of the given species.",
                      "type": "number"
                    },
                    "species": {
                      "description": "A species appearing in the equation.",
                      "minLength": 1,
                      "type": "string"
                    },
                    "unit": {
                      "description": "Unit of `amount`. Default \"mol\".",
                      "enum": [
                        "mol",
                        "g"
                      ],
                      "type": "string"
                    }
                  },
                  "required": [
                    "species",
                    "amount"
                  ],
                  "type": "object"
                },
                "target": {
                  "description": "The species to solve for.",
                  "minLength": 1,
                  "type": "string"
                },
                "targetUnit": {
                  "description": "Unit for the target result. Default \"mol\".",
                  "enum": [
                    "mol",
                    "g"
                  ],
                  "type": "string"
                }
              },
              "required": [
                "equation",
                "given",
                "target"
              ],
              "type": "object"
            },
            "bodyType": {
              "enum": [
                "json",
                "form-data",
                "text"
              ],
              "type": "string"
            },
            "method": {
              "enum": [
                "POST"
              ],
              "type": "string"
            },
            "type": {
              "const": "http",
              "type": "string"
            }
          },
          "required": [
            "type",
            "method",
            "bodyType",
            "body"
          ],
          "type": "object"
        }
      },
      "required": [
        "input"
      ],
      "type": "object"
    }
  }
}

curl "https://chemeq.openverbs.com/v1/stoichiometry"
# -> 402 Payment Required, accepts[] lists how to pay
# retry with a PAYMENT-SIGNATURE (or PAYMENT header) once paid

const res = await fetch("https://chemeq.openverbs.com/v1/stoichiometry");
if (res.status === 402) {
  const { accepts } = await res.json();
  // pay one of accepts[] via an x402 client, then retry with the payment header
}

import httpx
res = httpx.get("https://chemeq.openverbs.com/v1/stoichiometry")
if res.status_code == 402:
    accepts = res.json()["accepts"]
    # pay one of accepts[] via an x402 client, then retry with the payment header