In In re Heather P. (1989) 209 Cal. App. 3d 886, 891 [257 Cal. Rptr. 545], the mother of the minor claimed the procedure established under section 388 violated her due process rights because of the discretion it gave to the court to determine whether to conduct a hearing. Rejecting that argument, the court emphasized the principle that a parent's petition should be construed liberally in favor of granting a hearing. (Ibid.) The court in In re Heather P., supra, 209 Cal. App. 3d at page 891, construed the requirement in section 388 imposed on a parent to petition the juvenile court for a hearing in the context of dependency proceedings as a whole. The court stated as follows: "At each hearing until after the permanency plan, the mother had the right to present evidence that Heather could be returned home safely. by the time the permanency plan was formed, the court reasonably assumed the mother would not be able to eliminate the problems which required Heather's placement outside her home. After the permanency plan it was reasonable to require her to petition the court if she wished to present evidence that her circumstances had changed." (209 Cal. App. 3d at pp. 891-892.)