minimum (value, schema, opts) {
    // Must be a number
    const minimum = schema.minimum
    // Must be a boolean
    // Depends on minimum
    // default: false
    const exclusiveMinimum = schema.exclusiveMinimum
    if (typeof value === typeof minimum && !(exclusiveMinimum ? value > minimum : value >= minimum)) {
      return exclusiveMinimum
        ? makeError(value, `no less than nor equal to ${minimum}`, opts)
        : makeError(value, `no less than ${minimum}`, opts)
    }
  }
Validates the provided value against a minimum value defined by the Schema's `minimum` keyword
Validation succeeds if the value is a number and is greater than, or equal to, the value of this keyword.
http://json-schema.org/latest/json-schema-validation.html#anchor21

@name Schema.validationKeywords.minimum
@method
@param {*} value Number to validate against the keyword.
@param {object} schema Schema containing the `minimum` keyword.
@param {object} [opts] Configuration options.
@returns {(array|undefined)} Array of errors or `undefined` if valid.